It is common practice today to employ a ribbon cassette wherein there are two ribbon storage spools and a ribbon engageable by a print head of a printer is supplied from these spools. In at least one configuration of such a cassette, there are two capstans, alternately driven by the printer, and each being associated with and driving one of the two spools and in a direction wherein the ribbon is advanced by a capstan toward its associated spool. Only one of the drive rollers is rotated or rotates at one time, there being a drive connection on each side to a capstan, whereby, alternately, one or the other of the capstans is driven. A capstan drives, via a belt, the associated spool. When a ribbon has been driven its maximum length in one direction, the cassette is turned over and the other capstan is driven from the opposite side of the cassette. In order to effect this change, however, it is necessary for the user to uncouple the belt on one side and couple it between a capstan pulley and spool pulley on the opposite side. This is an inconvenient step and, of course, necessitates the provision of external belt drive pulleys and an external belt.
It is an object of this invention to eliminate the belt change step and to eliminate the structure which is required in such an exterior belt-type construction.